Pathophysiology of sarcopenia: Genetic factors and their interplay with environmental factors

The association between shorter disease course and sarcopenia in women with endometriosis: a retrospective analysis of NHANES 1999-2006

Endometriosis is a common gynecological disorder that is associated with chronic pelvic pain, infertility, and metabolic complications. Sarcopenia, characterized by progressive skeletal muscle loss, predominantly affects older adults. This study explored the incidence and risk factors for sarcopenia in endometriosis patients using the NHANES dataset, which included 373 participants. Endometriosis was confirmed through self-report questionnaire, and sarcopenia was diagnosed via dual-energy X-ray absorptiometry. Covariates encompassed age, race, marital status, education attainment, poverty income ratio, smoking habits, and comorbidities. Statistical analyses were conducted using SPSS version 26.0, incorporating four multivariate regression models. The average age was 40.3 and 40.0 years in endometriotic participants with and without sarcopenia, respectively. Minority ethnicity had higher odds for sarcopenia (OR 6.00, 95% CI 1.24-29.07). A disease duration of endometriosis less than five years was associated with higher sarcopenia risk (OR 4.83, 95% CI 2.57-9.09). Conversely, lower educational levels were linked to a reduced chance of developing sarcopenia (OR 0.42, 95% CI 0.21-0.86). These findings were consistent across all regression models, indicating that ethnic minority status, higher educational attainment, and shorter disease duration are significant risk factors for concurrent sarcopenia in endometriosis patients.

Targeting Muscle Regeneration with Small Extracellular Vesicles from Adipose Tissue-Derived Stem Cells-A Review

Extracellular vesicles (EVs) are membrane-bound structures released by cells carrying diverse biomolecules involved in intercellular communication. Small EVs are abundant in body fluids, playing a key role in cell signaling. Their natural occurrence and therapeutic potential, especially in the context of muscular disorders, make them a significant area of research. Sarcopenia, characterized by progressive muscle fiber loss, represents a pathological state in which EVs could offer therapeutic benefits, reducing morbidity and mortality. Recent studies have proposed an interplay between adipose tissue (AT) and skeletal muscle regarding sarcopenia pathology. AT dysregulation, as seen in obesity, contributes to skeletal muscle loss in a multifactorial way. While AT-derived stem cell (ATDSC) small EVs have been implicated in musculoskeletal homeostasis, their precise action in muscle regeneration remains incompletely understood. In this context, ATDSC-derived small EVs can stimulate skeletal muscle regeneration through improved proliferation and migration of muscle cells, enhancement of muscular perfusion, improvement of tendon and nerve regeneration, stimulation of angiogenesis, and promotion of myogenic differentiation. However, they can also increase skeletal muscle loss. Notably, this is the first comprehensive review to systematically examine the role of ATDSC-derived small EVs in sarcopenia.

Sarcopenia in Parkinson's disease: from pathogenesis to interventions

Parkinson's disease (PD) and sarcopenia are prevalent age-related conditions that often coexist in affected individuals. Sarcopenia is particularly common among PD patients, with severe cases affecting approximately one in five individuals with the disease. Furthermore, sarcopenia is closely linked to the accelerated progression of PD, diminished quality of life, greater susceptibility to falls and fractures, and increased mortality risk. Although the precise mechanisms remain unclear, numerous studies suggest that factors such as the accumulation of α-Synuclein in skeletal muscle, loss of motor neurons, inflammation, phosphate toxicity, hormonal dysregulation, vitamin D deficiency, intestinal flora imbalances, and dysfunction of the gut-muscle-brain axis contribute to sarcopenia in PD. Understanding these mechanisms provides valuable insights into the relationship between PD and sarcopenia and establishes a foundation for future research and therapeutic strategies. This review examines the mechanisms underlying sarcopenia in PD, methods for its screening and assessment, and potential avenues for future research, including strategies for risk reduction and treatment.

TLR/NLRP3 inflammasome signaling pathways as a main target in frailty, cachexia and sarcopenia

Mobility disability is a common condition affecting older adults, making walking and the performance of activities of daily living difficult. Frailty, cachexia and sarcopenia are related conditions that occur with advancing age and are characterized by a decline in muscle mass, strength, and functionality that negatively impacts health. Chronic low-grade inflammation is a significant factor in the onset and progression of these conditions. The toll-like receptors (TLRs) and the NLRP3 inflammasome are the pathways of signaling that regulate inflammation. These pathways can potentially be targeted therapeutically for frailty, cachexia and sarcopenia as research has shown that dysregulation of the TLR/NLRP3 inflammasome signaling pathways is linked to these conditions. Activation of TLRs with pathogen-associated molecular patterns (PAMPs or DAMPs) results in chronic inflammation and tissue damage by releasing pro-inflammatory cytokines. Additionally, NLRP3 inflammasome activation enhances the inflammatory response by promoting the production and release of interleukins (ILs), thus exacerbating the underlying inflammatory mechanisms. These pathways are activated in the advancement of disease in frail and sarcopenic individuals. Targeting these pathways may offer therapeutic options to reduce frailty, improve musculoskeletal resilience and prevent or reverse cachexia-associated muscle wasting. Modulating TLR/NLRP3 inflammasome pathways may also hold promise in slowing down the progression of sarcopenia, preserving muscle mass and enhancing overall functional ability in elderly people. The aim of this review is to investigate the signaling pathways of the TLR/NLRP3 inflammasome as a main target in frailty, cachexia and sarcopenia.

Cut-off values for the muscle mass indices determined using DXA in healthy Polish adults - a comparison to EWGSOP2 recommendation

BACKGROUND

Muscle mass measurements are vital for predicting health outcomes and diagnosing muscle disorders. This study provides reference data for appendicular lean mass (ALM) and total lean mass (TLM) in healthy Polish adults with normal muscle strength and physical performance as per EWGSOP2 guidelines.

METHODS

The study included healthy volunteers with normal muscle strength and functional status. Lean mass was measured using Hologic Horizon DXA. Mean values of TLM, ALM, fat-free mass (FFM), and indices (TLMI, ALMI, FFMI) were calculated for seven age groups (by decade). Cut-off points equivalent to T-scores of -1 and -2 standard deviations (SDs) below the young adult reference mean (ages 20-39) were determined.

RESULTS

Data from 1,111 participants (328 men, 46.3 ± 20 years; 783 women, 43.7 ± 23 years) were analyzed. In young adults, mean ALM was 28.1 kg (men) and 17.2 kg (women), and ALMI was 8.6 kg/m2 (men) and 6.1 kg/m2 (women). Low muscle mass cut-off points (2 SDs below) were 18 kg and 10.9 kg (ALM) and 6 kg/m2 and 4.3 kg/m2 (ALMI) for men and women, respectively. Men exhibited significantly greater lean mass than women across all age groups (P < 0.001). Lean mass declined with age in both genders, following a nonlinear pattern, except for ALMI in men.

CONCLUSIONS

This study provides the first population-based reference values for ALM and TLM in healthy Polish adults aged 20-89 years, integrating criteria for normal muscle strength and physical performance.

The Dietary Inflammatory Index and Sarcopenia in Older Adults in Four Chinese Provinces: A Cross-Sectional Study

Background: Sarcopenia associated with aging severely affects the quality of life of the elderly; diets have been shown to elicit an inflammatory response in the body, and diets that promote inflammation may lead to damage to muscles. The Dietary Inflammatory Index (DII) has been developed to quantify the inflammatory potential of individual diets. Therefore, this study aimed to investigate the association between the DII, sarcopenia and its components in elderly Chinese people. Methods: In this study, data were obtained from the China Nutrition Improvement Strategies and Applications for the Elderly Research Programme. An assessment of sarcopenia was carried out according to the Asian Working Group on Sarcopenia's (AWGS2019) criteria. The DII was calculated using food intake data obtained using the FFQ method, and then the quartile method was used to categorize the subjects into four groups. Multifactor logistic regression was conducted to examine the associations between DII, sarcopenia and its components. Results: This study included 993 subjects over the age of 65, and the prevalence of sarcopenia was 20.2%. The mean DII score of the study population was 0.99 ± 0.1. After adjusting for the confounders age, gender, marital status, and educational level, the risk of sarcopenia was 1.66 times higher in group Q4 than in group Q1 (p-trend < 0.05). However, this relationship is not statistically significant when other more confounding factors are added. Nevertheless, when further analyzing the relationship between DII and sarcopenia components, it was found that after adjusting the model, a higher DII was associated with a risk of muscle strength loss (OR = 1.65, p-trend < 0.05). Conclusions: Higher DII scores increase the risk of muscle strength loss in older adults. By guiding older adults to adopt a more anti-inflammatory diet, muscle health can be improved in terms of increased muscle strength. Further cohort or interventional studies are necessary to validate our findings.

Related factors of sarcopenia risk in Chinese older people - a cross-sectional study

Numerous factors, including age chronic disease, level of education, and depression, affect the health and function of skeletal muscles. However, it is still unclear which factors affect skeletal muscle health in older age groups across age range segments. Decision tree and logistic regression models were employed in this study to examine the factors that influence older adults' likelihood of developing sarcopenia. The database information of the China Health and Retirement Longitudinal Study (CHARLS) in 2015 was selected, and a sample of 2965 people who met the inclusion criteria was screened. Logistic regression research revealed that while height (p = 0.001, OR:0.979, 95%CI:0.967-0.992), triglycerides (p = 0.036, OR:0.999,95%CI:0.998-1.000), level of education (p = 0.004, OR:0.684,95%CI:0.530-0.883), and endowment insurance (p = 0.003, OR:0.598,95%CI: 0.427-0.839) were protective variables against sarcopenia in older adults, age (p < 0.001, OR:1.094,95%CI:1.079-1.110), depression (p = 0.003, OR:1.283,95%CI:1.089-1.512), and chronic disease(p < 0.012, OR:1.266,95%CI: 1.054-1.522) were risk factors for the condition. According to the decision tree model, the biggest determinant of an older person's chance of developing sarcopenia is age, which is followed by social communication, depression, chronic disease, level of education, and endowment insurance. In the aging Chinese population, sarcopenia risk is positively correlated with age, depression, and chronic disease, while it is adversely correlated with height, triglycerides, level of education, and endowment insurance. Level of education is the primary factor determining the risk of sarcopenia in older adults aged 60-69, while endowment insurance is the primary factor influencing the risk of sarcopenia in older adults aged 70-79. To prevent and intervene earlier in the beginning and progression of sarcopenia in the elderly, it is advised that knowledge of the condition be raised among the older population.

Clock-Sleep Communication

Rhythmicity is a characteristic feature of the inanimate universe. The organization of biological rhythms in time is an adaptation to the cyclical environmental changes brought on by the earth's rotation on its axis and around the sun. Circadian (L. Circa = "around or approximately"; diem = "a day") rhythms are biological responses to the geophysical light/dark (LD) cycle in which an organism adjusts to alterations in its internal physiology or external environment as a function of the time of day. Sleep has been considered a biological rhythm. Normal human sleep, an essential physiologic process, comprises two distinct phases: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. A mature adult human's sleep/wake cycle displays a circadian rhythm with a ~24-hour cycle. According to the two-process model of sleep regulation, the human sleep/wake cycle is orchestrated by circadian and homeostatic processes. Sleep homeostasis (a sleep-dependent process) and circadian rhythm (a sleep-independent process) are two biological processes controlling the sleep/wake cycle. There are also ultradian (< 24-hour) rhythms, including the NREM-REM sleep cycle, which has been extensively studied. The clock and sleep genes both influence sleep. In this overview, we have reviewed the circadian genes and their role in regulating sleep. Besides, the gene expression and biological pathways associated with sleep and circadian rhythm-associated diseases also have been highlighted.

Factors Affecting Handgrip Strength in Menopausal Women at High Risk of Sarcopenia: A National Population-Based Study

Background/Objectives: Hand grip strength (HGS) reflects muscle strength and is an important indicator of sarcopenia. There is a gap in the research regarding the determinants of relative HGS that take sex differences into account. Therefore, this study aimed to evaluate the association between relative HGS and physical, behavioral, and psychological factors in menopausal women from South Korea. Methods: This study used data obtained from the 7th National Health and Nutrition Examination Survey (2016-2018), which had a complex, stratified, and multistage sample design. A total of 2129 menopausal women aged between 40 and 64 were included in this cross-sectional study. To evaluate physical, behavioral, and psychological factors associated with relative HGS, a multiple regression analysis was used. Results: In this study, the sociodemographic factors that influenced relative HGS were education (high school: B = 0.03, p = 0.001; college: B = 0.04, p = 0.003) and marital status (live with: B = 0.04, p = 0.004). Among the physical factors, abdominal obesity (B = -0.16, p < 0.001) and comorbidities (B = -0.03, p = 0.026) were associated with a significantly lower relative HGS. Regarding behavioral factors, relative HGS was significantly lower for those who slept more than 8 h (B = -0.03, p = 0.041) than for those who slept 6-8 h. Regarding psychological factors, relative HGS was significantly higher for those with fair (B = 0.04, p = 0.001) and good (B = 0.06, p < 0.001) self-rated health. Conclusions: Relative HGS is associated with physical, behavioral, and psychological factors in menopausal women. These findings can inform research and guidelines for sarcopenia prevention using relative HGS as an indicator of health status.

Identifying Risk Factors for Presarcopenia in Early Middle Age

OBJECTIVE

This study aimed to determine whether risk factors for presarcopenia can be identified in a sample of early middle-aged men and women.

DESIGN

Prospective study.

SETTING

Longitudinal data from the Dunedin Multidisciplinary Health and Development Study were used to investigate the relationship between presarcopenia at age 45 years and selected early markers at ages 26, 32, and 38 years.

PARTICIPANTS

Longitudinal data from N=899 participants from the Dunedin Multidisciplinary Health and Development Study.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Presarcopenia was defined as low relative appendicular lean mass index assessed by dual energy x-ray absorptiometry and low strength assessed by grip strength. Logistic regressions were used to describe the association between selected markers and presarcopenia at age 45 years.

RESULTS

Multivariate logistic regression revealed that a higher body mass index (BMI) at ages 26, 32, and 38 years was associated with lower likelihood of presarcopenia at age 45 years in both men and women (odds ratio [OR] range, 0.46-0.64). Higher age-normative grip strength at age 38 years in both men and women (OR range, 0.88-0.92) was also associated with lower likelihood for presarcopenia. Lastly, lower self-perceived physical fitness level in men at age 38 years was associated with an increased likelihood of presarcopenia at age 45 years (OR, 9.35; 95% confidence interval, 3.28-26.70).

CONCLUSIONS

BMI and strength were associated with lower likelihood of presarcopenia during middle age. A higher likelihood of presarcopenia was associated with sex-specific lower self-perceived physical fitness. These modifiable biomarkers may serve as targets for clinical screening and early intervention aimed at slowing or preventing progression to sarcopenia in old age.

Identifying genetic determinants of sarcopenia-related traits: a Mendelian randomization study of druggable genes

BACKGROUND

Sarcopenia, characterized by progressive muscle mass and function loss, particularly affects the elderly, and leads to severe consequences such as falls and mortality. Despite its prevalence, targeted pharmacotherapies for sarcopenia are lacking. Utilizing large-sample genome-wide association studies (GWAS) data is crucial for cost-effective drug discovery.

METHODS

Herein, we conducted four studies to understand the putative causal effects of genetic components on muscle mass and function. Study 1 employed a two-sample Mendelian randomization (MR) on 15,944 potential druggable genes, investigating their potential causality with muscle quantity and quality in a European population (N up to 461,089). Study 2 validated MR results through sensitivity analyses and colocalization analyses. Study 3 extended validation across other European cohorts, and study 4 conducted quantitative in vivo verification.

RESULTS

MR analysis revealed significant causality between four genes (BLOC-1 related complex subunit 7, BORCS7; peptidase m20 domain containing 1, PM20D1; nuclear casein kinase and cyclin dependent kinase substrate 1, NUCKS1 and ubiquinol-cytochrome c reductase complex assembly factor 1, UQCC1) and muscle mass and function (p-values range 5.98 × 10-6 to 9.26 × 10-55). To be specific, BORCS7 and UQCC1 negatively regulated muscle quantity and quality, whereas enhancing PM20D1 and NUCKS1 expression showed promise in promoting muscle mass and function. Causal relationships remained robust across sensitivity analyses, with UQCC1 exhibiting notable colocalization effects (PP·H4 93.4 % to 95.8 %). Further validation and in vivo replication verified the potential causality between these genes and muscle mass as well as function.

CONCLUSIONS

Our druggable genome-wide MR analysis identifies BORCS7, PM20D1, NUCKS1, and UQCC1 as causally associated with muscle mass and function. These findings offer insights into the genetic basis of sarcopenia, paving the way for these genes to become promising drug targets in mitigating this debilitating condition.

The Relationship Between MOTS-c K14Q Polymorphism and Sarcopenia, Blood Lipids, and Mental Health in Older Korean Adults

Background/objectives: An East Asian-specific 1382A>C polymorphism in the mitochondrial open reading frame of the 12S rRNA type-c results in an amino acid substitution from Lys (K) to Gln (Q) at the 14th amino acid residue. This study investigated the association between m.1382A>C polymorphism and sarcopenia, blood lipids, and mental health in older Korean adults. Methods: The study included 683 community-dwelling Korean adults (345 men and 338 women) aged 65 years and older. The m.1382A>C polymorphism was genotyped with a 7500 real-time PCR system. Handgrip strength (HGS) was measured, and appendicular skeletal muscle (ASM) mass was calculated. Demographics, blood lipids, falling risk, nutritional intake, cognition function, and depression were additionally measured. Results: Men carrying the C allele had significantly higher ASM (21.6 ± 3.0 vs. 19.5 ± 2.2 kg, p = 0.018), ASM/height2 (7.76 ± 0.76 vs. 7.14 ± 0.62 kg/m2, p = 0.012), lean mass (53.3 ± 6.2 vs. 46.5 ± 4.0 kg, p < 0.001), left HGS (33.3 ± 5.0 vs. 28.9 ± 4.0 kg, p = 0.010), and right HGS (35.6 ± 5.3 vs. 30.9 ± 4.3 kg, p = 0.009) than men carrying the A allele. The genotype differences in ASM (p = 0.017), ASM/height2 (p = 0.011), lean mass (p < 0.001), left HGS (p = 0.010), and right HGS (p = 0.009) remained significant even after adjusting for all measured covariates. By contrast, no significant differences in other measured parameters were found between women carrying the A and C alleles. Conclusions: Our study findings indicate that the m.1382A>C polymorphism may be used as a genetic biomarker of age-related sarcopenia in older Korean men.

Advancements in sarcopenia diagnosis: from imaging techniques to non-radiation assessments

Sarcopenia is a prevalent condition with significant clinical implications, and it is expected to escalate globally, demanding for effective diagnostic strategies, possibly at an early stage of the disease. Imaging techniques play a pivotal role in comprehensively evaluating sarcopenia, offering insights into both muscle quantity and quality. Among all the imaging techniques currently used for the diagnosis and follow up of sarcopenia, it is possible to distinguish two classes: Rx based techniques, using ionizing radiations, and non-invasive techniques, which are based on the use of safe and low risk diagnostic procedures. Dual-energy x-ray Absorptiometry and Computed Tomography, while widely utilized, entail radiation exposure concerns. Ultrasound imaging offers portability, real-time imaging, and absence of ionizing radiation, making it a promising tool Magnetic Resonance Imaging, particularly T1-weighted and Dixon sequences, provides cross- sectional and high-resolution images and fat-water separation capabilities, facilitating precise sarcopenia quantification. Bioelectrical Impedance Analysis (BIA), a non-invasive technique, estimates body composition, including muscle mass, albeit influenced by hydration status. Standardized protocols, such as those proposed by the Sarcopenia through Ultrasound (SARCUS) Working Group, are imperative for ensuring consistency across assessments. Future research should focus on refining these techniques and harnessing the potential of radiomics and artificial intelligence to enhance diagnostic accuracy and prognostic capabilities in sarcopenia.

Mendelian randomization analysis reveals no causal relationship between thyroid function and sarcopenia-related traits

Background

Recent research has indicated a potential association between thyroid function and sarcopenia, but the specific mechanisms and a definitive causal relationship have yet to be established. Therefore, the objective of this study is to examine the potential causal connection between thyroid function and sarcopenia-related traits, including hand-grip strength, appendicular lean mass (ALM), and walking pace.

Methods

The study used a bi-directional two-sample MR design, with thyroid function examined as the exposure and sarcopenia-related traits as the outcome in the first stage, and then reversed in the second stage. The genetic instruments for thyroid function were obtained from a comprehensive meta-analysis involving 271,040 participants. Data on sarcopenia-related traits based on GWASs were collected from the UK Biobank, which includes up to 461,026 European participants. The estimates for MR were calculated using the inverse-variance weighted (IVW) method, and several sensitivity analyses were performed.

Results

After applying the Bonferroni correction for multiple testing, our MR analyses revealed no significant impact of thyroid function liability on sarcopenia-related traits. Similarly, our reverse MR analysis did not provide evidence supporting the influence of liability to sarcopenia-related traits on thyroid function. The results of the primary IVW MR analyses were largely in line with those obtained from our sensitivity MR analyses.

Conclusion

Our research findings do not suggest a link between thyroid function and sarcopenia-related traits. The associations identified in epidemiological studies may be influenced, at least in part, by shared biological mechanisms or environmental confounders.

Circulating Amino Acid Concentration after the Consumption of Pea or Whey Proteins in Young and Older Adults Affects Protein Synthesis in C2C12 Myotubes

As older adults tend to reduce their intake of animal-source proteins, plant-source proteins may offer valuable resources for better protein intake. The aim of this study was to assess whether the pea proteins can be used to achieve blood amino acid levels that stimulate muscle protein synthesis. We measured variations in plasma amino acid concentrations in young and older adults given pea (NUTRALYS® S85 Plus) or whey proteins either alone or in a standardized meal. The effect of amino acid concentrations on protein synthesis in C2C12 myotubes was determined. In terms of results, plasma amino acid concentrations reflected the difference between the amino acid contents of whey and pea proteins. Blood leucine showed a greater increase of 91 to 130% with whey protein compared to pea protein, while the opposite was observed for arginine (A greater increase of 147 to 210% with pea compared to whey). Culture media prepared with plasmas from the human study induced age-dependent but not protein-type-dependent changes in myotube protein synthesis. In conclusion, pea and whey proteins have the same qualities in terms of their properties to maintain muscle protein synthesis. Pea proteins can be recommended for older people who do not consume enough animal-source proteins.

Research Progress on the Effect and Mechanism of Exercise Intervention on Sarcopenia Obesity

With the increasingly severe situation of obesity and population aging, there is growing concern about sarcopenia obesity (SO). SO refers to the coexistence of obesity and sarcopenia, which imposes a heavier burden on individuals and society compared to obesity or sarcopenia alone. Therefore, comprehending the pathogenesis of SO and implementing effective clinical interventions are vital for its prevention and treatment. This review uses a comprehensive literature search and analysis of PubMed, Web of Science, and CNKI databases, with search terms including "Sarcopenic obesity", "exercise", "cytokines", "inflammation", "mitochondrial quality control", and "microRNA", covering relevant studies published up to July 2024. The results indicate that the pathogenesis of SO is complex, involving mechanisms like age-related changes in body composition, hormonal alterations, inflammation, mitochondrial dysfunction, and genetic and epigenetic factors. Regarding exercise interventions for SO, aerobic exercise can reduce fat mass, resistance exercise can increase skeletal muscle mass and strength, and combined exercise can achieve both, making it the optimal intervention for SO. The potential mechanisms by which exercise may prevent and treat SO include regulating cytokine secretion, inhibiting inflammatory pathways, improving mitochondrial quality, and mediating microRNA expression. This review emphasizes the effectiveness of exercise interventions in mitigating sarcopenic obesity through comprehensive analysis of its multifactorial pathogenesis and the mechanistic insights into exercise's therapeutic effects. Understanding these mechanisms informs targeted therapeutic strategies aimed at alleviating the societal and individual burdens associated with SO.

A Digital Platform for Home-Based Exercise Prescription for Older People with Sarcopenia

Digital therapeutics refers to smartphone applications, software, and wearable devices that provide digital solutions to improve healthcare delivery. We developed a digital platform to support the GYM (Grow Your Muscle) study, an ongoing 48-week randomized, controlled trial on reduction of sarcopenia through a home-based, app-monitored physical exercise intervention. The GYM platform consists of a smartphone application including the exercise program and video tutorials of body-weight exercises, a wearable device to monitor heart rate during training, and a website for downloading training data to remotely monitor the exercise. The aim of this paper is to describe the platform in detail and to discuss the technical issues emerging during the study and those related to usability of the smartphone application through a retrospective survey. The main technical issue concerned the API level 33 upgrade, which did not enable participants using the Android operating systems to use the wearable device. The survey revealed some problems with viewing the video tutorials and with internet or smartphone connection. On the other hand, the smartphone application was reported to be easy to use and helpful to guide home exercising. Despite the issues encountered during the study, this digital-supported physical exercise intervention could provide useful to improve muscle measures of sarcopenia.

Telomere Length is Associated with the Prevalence, Persistence, and Incidence of Sarcopenia

BACKGROUND

Telomere length (TL) shortening has been identified as a marker of aging and associated with adverse health outcomes, but evidence of its association with sarcopenia is inconclusive.

AIMS

Estimate the cross-sectional and prospective associations between TL and sarcopenia.

METHODS

We used data from Waves 3 and 4 (2017, 2021) of the Study on Global Aging and Adult Health in Mexico (SAGE-Mexico). The cross-sectional sample consisted of 1,738 adults aged 50 and older, and the longitudinal sample consisted of 1,437. Relative TL was determined by real-time quantitative polymerase chain reaction (qPCR) on DNA extracted from saliva samples and quantified as the telomere/single-copy gene (T/S) ratio. Sarcopenia was defined according to the European Working Group on Sarcopenia in Older People (EWGSOP2).

RESULTS

The mean salivary TL was 1.50 T/S units (95% CI: 1.49-1.52). The baseline prevalence of sarcopenia was 13.3% (95% CI: 9.8-16.8%). The incidence and persistence of sarcopenia were 6.8% (95% CI: 5.0-9.5%) and 7.0% (95% CI: 5.1-9.6%), respectively. The results showed that a one standard deviation decrease in TL was cross-sectionally associated with higher odds of sarcopenia (OR = 1.31; 95% CI: 1.03-1.67) and prospectively with a higher incidence (RRR = 1.55; 95% CI: 1.06-2.25) and persistence (RRR = 1.50; 95% CI: 1.01-2.24) of sarcopenia.

CONCLUSIONS

Older adults with shorter TL had higher rates of incident and persistent sarcopenia. Implementation of interventions to delay the decline of TL in older adults is warranted. Further translational studies are needed to elucidate the effects of exercise or diet on DNA repair in the telomeric region and their associations with sarcopenia.

Mapping the causal associations of cytokines with sarcopenia and aging traits: Evidence from bidirectional Mendelian randomization

BACKGROUND

Cytokines and growth factors may serve as a bridge in studying the causal relationships between inflammaging and sarcopenia due to their roles in inflammaging. In this study, we aim to explore the causal association of cytokines with sarcopenia and aging traits and further identify the significant inflammation factors.

METHODS

Bidirectional Mendelian randomization (MR) analysis was used to identify the causality. Forty-one kinds of circulation cytokines and growth factors were set as exposures, and the data were from a summary genome-wide association study (GWAS) containing three cohorts with 8293 healthy participants of European ancestry from 1983 to 2011. Hand grip strength, adjusted appendicular lean mass (AALM), usual walking pace, moderate-to-vigorous physical activity (MVPA) levels, able to walk or cycle unaided for 10 min (AWCU10) and telomere length were selected as outcomes. Data for outcomes were obtained from meta-GWAS and the UK Biobank, and sample sizes ranged from 69 537 to 472 174. Low hand grip strength was defined by the European Working Group on Sarcopenia in Older People (EWGSOP) and Foundation for the National Institutes of Health (FNIH) cut-off points, respectively. Other outcome traits were defined and measured according to the UK Biobank and raw cohorts' criteria. We set two significance thresholds for single nucleotide polymorphisms (SNPs) associated with exposures to obtain adequate SNPs (5 × 10-6 and 5 × 10-8). Inverse-variance weighted, MR-Egger and weighted median were employed to estimate the causality.

RESULTS

Twenty-seven factors were identified to relate to sarcopenia and aging traits causally, and most were associated with only one outcome trait. IL16 (interleukin-16), CTACK (cutaneous T-cell attracting chemokine), MIP1b (macrophage inflammatory protein 1b) and PDGFbb (platelet-derived growth factor BB) were proven to relate causally to at least one sarcopenia and aging trait in both analyses with two significance thresholds. IL16 was causally associated with hand grip strength (0.977 [0.956-0.998] for EWGSOP and 0.933 [0.874-0.996] for FNIH), AALM (0.991 [0.984, 0.998]), MVPA (0.997 [0.995-1.000]) and AWCU10 (1.008 [1.003-1.013]). CTACK was proven to relate causally to hand grip strength (1.013 [1.007-1.019] for EWGSOP and 1.090 [1.041-1.142] for FNIH), AWCU10 (0.990 [0.986-0.994]) and telomere length (0.998 [0.983-0.994]). The results indicated that MIP1b has a causal effect on hand grip strength (1.032 [1.001-1.063] for EWGSOP), AWCU10 (0.994 [0.988-1.000] and 0.993 [0.988-0.998]) and telomere length (1.006 [1.000-1.012]). PDGFbb may causally relate to AALM (1.016 [1.001-1.030]) and telomere length (1.011 [1.007-1.015]). Reserve MR analyses also proved their unidirectional causal effects.

CONCLUSIONS

Twenty-seven factors were causally related to sarcopenia and aging traits, and the causal effects of IL16, CTACK, MIP1b and PDGFbb were proven in both analyses with two significance thresholds.

Steatotic Liver Disease: Pathophysiology and Emerging Pharmacotherapies

Steatotic liver disease (SLD) displays a dynamic and complex disease phenotype. Consequently, the metabolic dysfunction-associated steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH) therapeutic pipeline is expanding rapidly and in multiple directions. In parallel, noninvasive tools for diagnosing and monitoring responses to therapeutic interventions are being studied, and clinically feasible findings are being explored as primary outcomes in interventional trials. The realization that distinct subgroups exist under the umbrella of SLD should guide more precise and personalized treatment recommendations and facilitate advancements in pharmacotherapeutics. This review summarizes recent updates of pathophysiology-based nomenclature and outlines both effective pharmacotherapeutics and those in the pipeline for MASLD/MASH, detailing their mode of action and the current status of phase 2 and 3 clinical trials. Of the extensive arsenal of pharmacotherapeutics in the MASLD/MASH pipeline, several have been rejected, whereas other, mainly monotherapy options, have shown only marginal benefits and are now being tested as part of combination therapies, yet others are still in development as monotherapies. Although the Food and Drug Administration (FDA) has recently approved resmetirom, additional therapeutic approaches in development will ideally target MASH and fibrosis while improving cardiometabolic risk factors. Due to the urgent need for the development of novel therapeutic strategies and the potential availability of safety and tolerability data, repurposing existing and approved drugs is an appealing option. Finally, it is essential to highlight that SLD and, by extension, MASLD should be recognized and approached as a systemic disease affecting multiple organs, with the vigorous implementation of interdisciplinary and coordinated action plans. SIGNIFICANCE STATEMENT: Steatotic liver disease (SLD), including metabolic dysfunction-associated steatotic liver disease and metabolic dysfunction-associated steatohepatitis, is the most prevalent chronic liver condition, affecting more than one-fourth of the global population. This review aims to provide the most recent information regarding SLD pathophysiology, diagnosis, and management according to the latest advancements in the guidelines and clinical trials. Collectively, it is hoped that the information provided furthers the understanding of the current state of SLD with direct clinical implications and stimulates research initiatives.

Assessing causality between inflammatory bowel diseases with frailty index and sarcopenia: a bidirectional Mendelian randomization study

BACKGROUND

Previous studies have found that frailty and sarcopenia are commonly diagnosed in inflammatory bowel disease (IBD) patients, indicating an association between these conditions. Nonetheless, the cause‒effect connection between IBD, frailty, and sarcopenia remains unclear.

METHODS

We sourced the genetic variants for the exposures and outcomes from publicly accessible, extensive genome-wide association studies (GWAS). Specifically, we obtained IBD data from the International IBD Genetics Consortium, frailty index (FI) data from the United Kingdom Biobank and Swedish TwinGene, and sarcopenia data from a recent GWAS meta-analysis. Five methods, including inverse variance weighted (IVW), simple mode, MR-Egger, weighted mode, and the weighted median, were used to proceed with MR estimates. We also performed heterogeneity and horizontal pleiotropy tests.

RESULTS

Our results indicated a positive causal relationship between ulcerative colitis (UC) (IVW: β = 0.014, 95% CI, 0.006 to 0.021, p = 0.001) and Crohn's disease (CD) (IVW: β = 0.012; 95% CI, 0.006 to 0.018, p = 2e-04) with the FI. However, we uncovered no proof of a cause-and-effect relationship between UC (IVW: β = 0.001, 95% CI, -0.015 to 0.017, p = 0.344) or CD (IVW: β = 0.003, 95% CI, -0.009 to 0.015, p = 0.214) and sarcopenia. Additionally, in the inverse order, we also discovered no cause-and-effect connection between FI or sarcopenia on UC or CD in this study.

CONCLUSION

The MR analysis showed a positive causal association between IBD and FI, indicating that IBD patients may exhibit aging-related characteristics. Therefore, frailty assessments should be conducted as early as possible in IBD patients.

Leveraging Biomaterial Platforms to Study Aging-Related Neural and Muscular Degeneration

Aging is a complex multifactorial process that results in tissue function impairment across the whole organism. One of the common consequences of this process is the loss of muscle mass and the associated decline in muscle function, known as sarcopenia. Aging also presents with an increased risk of developing other pathological conditions such as neurodegeneration. Muscular and neuronal degeneration cause mobility issues and cognitive impairment, hence having a major impact on the quality of life of the older population. The development of novel therapies that can ameliorate the effects of aging is currently hindered by our limited knowledge of the underlying mechanisms and the use of models that fail to recapitulate the structure and composition of the cell microenvironment. The emergence of bioengineering techniques based on the use of biomimetic materials and biofabrication methods has opened the possibility of generating 3D models of muscular and nervous tissues that better mimic the native extracellular matrix. These platforms are particularly advantageous for drug testing and mechanistic studies. In this review, we discuss the developments made in the creation of 3D models of aging-related neuronal and muscular degeneration and we provide a perspective on the future directions for the field.